Wood ear

Appearance

The fruit body of A. auricula-judae is normally 3 to 8 centimetres (1.2 to 3.1 in) across, but can be as much as 12 centimetres (4.7 in). It is distinctively shaped, typically being reminiscent of a floppy ear, though the fruit bodies can also be cup-shaped. It is normally attached to the substrate laterally and sometimes by a very short stalk. The species has a tough, gelatinous, elastic texture when fresh, but it dries hard and brittle. The outer surface is a bright reddish-tan-brown with a purplish hint, often covered in tiny, downy hairs of a grey colour. It can be smooth, as is typical of younger specimens,[10] or undulating with folds and wrinkles. The colour becomes darker with age. The inner surface is a lighter grey-brown in colour and smooth. It is sometimes wrinkled, again with folds and wrinkles, and may have "veins", making it appear even more ear-like.

Microscopic features

The spores of A. auricula-judae are long and sausage shaped, ranging in size from 16 to 18 micrometres (μm) long by 6 to 8 μm thick. The spores themselves are white, cream or yellowish, and are hyaline. The spores can sometimes be seen in a whitish mass on the underside of the fruit body. The species has elongated cylindrical basidia with three transverse septa (internal cross-walls dividing the hyphae). Basidia 60-72x 4-7.5μm; sterigmata lateral, well developed, 3-4.5μm long. Spores smooth, hyaline, reniform to allantoid, 14-18 Χ 6-8μm, guttulate. Hairs on the fruit body are from 85 to 100 μm in length, and 5 to 6 μm in diameter. They are hyaline, lack a central strand and have rounded tips. They do not grow in dense tufts.

Naming

Its specific epithet is derived from the belief that Judas Iscariot hanged himself from an elder tree; the common name "Judas's ear" eventually became "Jew's ear", while today "jelly ear" and other names are sometimes used.

Auricularia auricula-judae

Habitat

Auricularia auricula-judae grows upon the wood of deciduous trees and shrubs, favouring elder. In up to 90% of cases, the mushroom is found on elder, but it is often incorrectly assumed to grow exclusively on elder. It has also been recorded on Acer pseudoplatanus (known in the United Kingdom as sycamore), beech, ash, spindle, and in one particular case, the sycamore draining board of an old sink in Hatton Garden. Recently, A. auricula-judae has been recorded from semi-evergreen to evergreen and wet evergreen shola forests in the Western Ghats, India. This species occurs scattered and in clusters on dead or dying branches of trees, on main trunk, decaying logs, etc. This species occurs during the monsoon period in large imbricate clusters and under high humid conditions produces exceptionally large sized basidiomes. A. auricula-judae growing in wet evergreen and shola forests shows remarkable variation in size, shape and colour. In Australia, it is found in Eucalyptus woodland and rainforests; in the rainforests, it can grow in very large colonies on fallen logs. It favours older branches, where it feeds as a saprophyte (on dead wood) or a weak parasite (on living wood), and it causes white rot.

Commonly growing solitarily, it can also be gregarious (in a group) or caespitose (in a tuft). Spores are ejected from the underside of the fruit bodies with as many as several hundred thousand an hour, and the high rate continues when the bodies have been significantly dried. Even when they have lost some 90% of their weight through dehydration, the bodies continue to release a small number of spores. It is found all year, but is most common in autumn. It is widespread throughout temperate and sub-tropical zones worldwide, and can be found across Europe, North America, Asia, Australia, South America and Africa. There has been some debate about the appearance of the species in the tropics; while it has been frequently reported there, Bernard Lowy, in an article on Auricularia, said that "of the specimens I have examined, none could be assigned here".